Hardy Kiwis for Cold Climate Gardeners

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The conventional kiwifruit is fine in mild climate, but you need extra-tough kiwis where winters are cold. Photo: homesteadersonline

Who wouldn’t recognize a kiwifruit, the goose egg-sized fruit with a fuzzy brown outer skin and delicious green flesh inside? They’re sold in supermarkets everywhere all year long. The fruit comes not from a tree, like an apple or cherry, but form a vigorous twining woody vine: the kiwi, kiwifruit or Chinese gooseberry: Actinidia deliciosa, formerly A. chinensis.

Traditional kiwifruit whole and cut in half.
The traditional fuzzy kiwi: delicious, but none too hardy. Photo: André Karwath, Wikimedia Commons

While the kiwifruit is abundantly found in supermarkets ready to eat, it’s not all that hardy. It’s limited to hardiness zones 8 to 9; sometimes, with special care, to zone 7. Some of the readers of this blog can grow it, for example those in the southern US or on its west coast, milder parts of Europe and temperate regions of Afric, Asia, Australia and New Zealand, but most live in cool to cold temperate climates. The best you could do would be to grow this vigorous, domineering plant in a greenhouse. Good luck with that!

Fortunately, there are other species of Actinidia, ones with small fruit often called kiwiberries, that are very hardy and which can easily be grown in outdoors in all but the coldest climates, in particular A. kolomikta and A. arguta. Yet, they don’t absolutely require subzero winters, so can also adapt to mild climates. In other words, these hardier kiwis can be grown by just about anyone outside the tropics. Maybe there is a place for a few of these hardy kiwis in your garden?

Vigorous Climbers

Hardy kiwi covering a pagoda
A hardy kiwi (Actinidia arguta) can practically take over a pergola if not pruned back occasionally. Photo: ladnydom.pl

Hardy kiwis are vigorous climbers with twining woody branches that twist around their support. They therefore require a solid support: a trellis, pergola, arbor or other. You can also let them climb a tree, but then, how will you harvest the fruits? Especially since kiwi vines can reach more than 35 feet (10 m) in height! 

Another possibility is to grow them as large shrubs, 6 to 10 feet (2 to 3 m) in height and as much in width. You can easily create this effect simply by regularly snipping off any branches that grow too long. By preventing the plant from climbing, it will reluctantly take on a shrublike form.

Flower of hardy kiwi
To fully enjoy kiwi flowers, you have to be underneath the plant, looking up. Photo: amazon.de

Kiwifruit blooms profusely in the spring, producing small, fragrant, but relatively inconspicuous white flowers, since they are produced among the leaves and are therefore rather hidden. They are best appreciated when grown on a pergola or arbor where they can be admired from below. Suddenly the otherwise hidden flowers dangle down over your head by the hundreds if not the thousands! Quite a display!

It Takes Two To…

However, it’s very important to plant hardy kiwis of both sexes. That’s because the male and female flowers are produced on separate plants (the’re dioecious). So, you need 1 male plant for a maximum of 9 female plants; otherwise you won’t have fruit.

Hardy kiwis can be grown in the sun or shade in almost any well-drained soil, but preferably in rich and rather moist conditions, as that gives the most abundant fruits. A kiwi plant can easily live 150 to 200 years. Just plant yours in spring or fall … and wait patiently, as, like most fruiting plants, they usually take a few years before they start to produce fruit.

Kiwiberries

Kiwiberries cut in half, held in a hand
Kiwiberries are eaten without peeling. Photo: banggood.in

The fruits of hardy kiwis are small and produced in clusters, like grapes. Since they aren’t covered with fuzz, there is no need to peel them: just pop them in your mouth and eat them whole. They ripen in late summer or fall and are often difficult to see, as most are green, almost the same color as the foliage. Few change color when ripe, although there are some exceptions to that rule, as some varieties of Actinidia arguta, like ‘Mirzan’, do turn red at maturity. 

Usually, the best way to tell the fruits are ripe is to touch them. They soften a bit at maturity, so a bit of a squeeze will tell when to harvest.

Two Kiwis That Tolerate the Cold

Arctic kiwi

Map showing original distribution of arctic kiwi
The arctic kiwi is native to mountainous and northern areas of Asia. Ill.: http://www.plantsoftheworldonline.org

The hardiest kiwi is the so-called arctic kiwi, A. kolomikta, native to northern Asia, particularly Siberia and China. It doesn’t really grow in the Arctic (the common name is slightly exaggerated), but still, plants in the northernmost part of its range are not that far from the Arctic Circle. Plus, it can take temperatures down to -40 °F/C. 

Oddly, I keep seeing websites that underestimate its hardiness: commonly, they give zone 4. Calculate instead hardiness zone 3 or even, for some cultivars, zone 2. In other words, if you can garden in your climate, you can likely grow this plant. (My apologies to the very rare people who do garden in zone 1!)

Variegated pink and white leaves of Arctic Beauty kiwi
Most arctic kiwis are somewhat variegated. Some, like this ‘Arctic Beauty’, distinctly so. Photo: dewilde.nl

The arctic kiwi is actually more commonly grown as an ornamental plant, because its leaves are often abundantly variegated pink and white. 

Unfortunately for fruit-loving gardeners, most of the arctic kiwis sold in garden centers are male plants, the claim being made that male plants have the most colorful foliage. In fact, though, leaf coloration seems to be spread unevenly through both male and female clones of hardy kiwi. Many females are variegated too and some male clones, barely so. However, the most heavily variegated cultivar on the market is indeed a male clone, often sold with no name or under the cultivar name ‘Arctic Beauty’. If you grow arctic kiwis from seed and choose plants with the greatest variegation, you’ll inevitably find female plants among the lot. So, if you want to play the role of hybridizer and produce a female plant with brilliantly colorful leaves, go for it!

The arctic kiwi begins to produce fruit at a relatively young age, after about 3 years. The fruits ripen early, in August or September, as befits a fruit adapted to cold climates where summers are often short. The main flaw of this kiwi, though, is that the fruits drop off the plant soon after ripening, so it’s easy to miss the harvest window if you are not there at just the right time.

Aromatnaya arctic kiwi with fruits
Ripe fruits of the arctic kiwi ‘Aromatnaya’. Photo: centrosad.ru

As mentioned, the most common cultivar is the heavily variegated male cultivar ‘Arctic Beauty’, but there are other male clones. And, of course, you’ll want a male plant to pollinate your females. Among the female cultivars are ‘Aromatnaya’, ‘Krupnopladnay’, ‘Pavlovskaya’ and ‘Sentyabraskaya’ (‘September Sun’). 

If the names seem Russian to you, you’re right. This fruit has been, until recently, largely developed in Russia.

Hardy Kiwi

Geneva hardy kiwi showing reddish fruits
‘Geneva’ is a hardy kiwi with fruits that redden at maturity, a fairly unusual trait. Photo: bambooplants.ca

Another kiwi to try in colder regions is A. arguta, often referred to simply as “hardy kiwi”, although it’s not nearly as hardy as the arctic kiwi.

Its foliage is entirely green, it’s so is less ornamental than the foliage of the arctic kiwi, and it’s slower to start producing fruit, usually only doing so after 5 to 9 years. It’s not actually that well adapted to truly cold climates, either. Perhaps zone 4b, max. North of that, the late-maturing fruits (they often don’t ripen until the end of September or October) are often killed by frost. If frost threatens yours, harvest them: they will continue to ripen indoors, but won’t be as sweet as fruits that ripened on the vine.

Wide variety of different hardy kiwi fruits
Hardy kiwis grown from seed show a wide range of forms, sizes and colors. Photo: etsy.com

Male cultivars for pollination include ‘Weiki’ and ‘Meader’, but are often sold without a name other than “male”. There are dozens of female cultivars, including ‘Ananasnaya’ (‘Anna’), ‘Dunbarton Oaks’, ‘Geneva’, ‘Ken’s Red’ and ‘Mirzan’.

The Least Hardy Hardy Kiwi

Issai kiwi with fruit
‘Issai’ can fruit abundantly, but only in mild climates and only with a male pollinator nearby. Photo: halifaxperennials.ca

The most popular hardy kiwi, widely sold everywhere and often the only hardy kiwi offered, is ‘Issai’, a Japanese hybrid. However, it doesn’t live up to its reputation, especially in cold climates, and, in many situations, is a very poor choice indeed.

You hear a lot about the advantages of ‘Issai’ and at least one is true. It’s claimed to be able to set fruit when very young. Indeed, ‘Issai’ means “first year” in Japanese. Actually, it usually takes 2 to 3 years to produce its first fruits, but that’s still very young for a kiwifruit. So, give it full points for speed to first fruiting.

Next, merchants often claim it’s both male and female and self-pollinates. Thus, it’s a space saver: you only need one plant to get fruit. In fact, though, ‘Issai’ is 100% female, but somewhat parthenocarpic: it can produce a limited amount of fruit without pollination. However, if you want abundant production, you still need to plant a male A. arguta plant as a pollinator. So, take off a few points there.

And thirdly, the claim that most bothers me, since I live in a colder zone myself, is that ‘Issai’ is a hardy kiwi. In fact, it is not a true hardy kiwi (A. arguta), but a hybrid between the hardy kiwi (A. arguta) and the subtropical russet kiwi (A. rufa). It seems to have inherited enough subtropical genes from its A. rufa parent to make it unsuitable for growing beyond zone 6. North of that and it gets killed back by the cold most winters or, at least, its dormant flower buds are killed, and therefore it neither blooms nor fruits most years. Still, the label says zone 4 and gardeners in zones 4 and 5 plant it, confidently awaiting a good harvest. Most never get to taste a single fruit. Take off any remaining points there!

You’d think garden centers in colder climates would pull it from their shelves and only offer truly hardy varieties, but no such luck. Most still offer ‘Issai’ to gullible gardeners and, indeed, it’s generally the only “hardy” kiwi they sell. I must point out that this happens not only in those know-nothing box stores that regularly sell climatically inappropriate plants, but in local garden centers and nurseries in cold climates that should know better. Shame on you for scamming your clients! 

In short, in cold climates, zones 2 to 5, ‘Issai’ isn’t as much a kiwifruit as a real lemon!

Where to Find Hardy Kiwi Plants

Sadly, you won’t often find acceptable hardy kiwis in local garden centers. You’ll have to turn to a specialist fruit nursery and very likely will need to order them by mail. Here are a few sources:

Canada
Nutcracker Nursery & Tree Farm 
BambooPlants.ca.

USA
Planting JusticeRaintree Nursery 
One Green World.

Europe
Pépinières Quissac 
Pépinière Villeroy.

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Good luck with your cold-climate kiwis! They can be truly easy-to-grow plants with abundant and delicious fruit that any gardener would be proud to grow … but you still have to choose the right ones!

Is My Kiwi a Male or a Female?

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20170617A University of Minnesota Extension

Arctic kiwi in fruit. Photo: University of Minnesota Extension

You planted a hardy kiwi (Actinidia arguta, zone 4b) or an arctic kiwi (Actinidia kolomikta, zone 3) a few years ago, and it hasn’t yet produced any fruit. Then you discovered you actually had to plant at least two kiwis, one male and one female, because the plant is dioecious (male and female flowers appear on separate plants). So you want to plant a spouse for your lonely kiwi, but you can’t find the label that (hopefully) indicated the plant’s sex. How can you tell if your kiwi is a male or a female?

You have to wait until it blooms. It’s really only by looking closely at the flower when it blooms in June—in fact, actually touching it!—that you can tell the two apart. Here’s what to look for:

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Abundant stamens bearing yellow pollen show this plant to be a male. Photo: Apple2000, Wikimedia Commons

The male flower is filled with thin stamens topped in yellow pollen. When you touch them, yellow pollen sticks to your finger.

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Female flowers have a cluster of sticky white stigmas in the center. Photo: Mnolf, Wikimedia Commons

The female flower produces flowers with peripheral stamens, but they’re sterile and don’t produce pollen. In the center, however, you’ll see white stigmas that project outward beyond the stamens and they’ll feel sticky to the touch.

There you go! Simple, isn’t it? But do have to check while the plant is in bloom.

Leaf Color Can (Sometimes) Help

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The popular cultivar Actinidia kolomikta ‘Arctic Beauty’, a male, is grown as an ornamental for its variegated pink and white leaves. Photo: laidbackgardener@wordpress.com

You can sometimes make a good guess about the sex of an arctic kiwi (A. kolomikta) by studying its leaf color. The most commonly sold cultivar, A. kolomikta ‘Arctic Beauty’, offers foliage heavily variegated white and pink … and it’s a male. You can therefore assume that if your kiwi is very colorful, it’s probably a male. However … female cultivars of A. kolomikta too are usually variegated to varying degrees and other male cultivars may be entirely green or only slightly variegated, so the color of the foliage is more an indication of plant’s sex than a proof.

Still No Fruit

You did plant at least one male and female, but it’s been years and there are no fruits yet. What’s going wrong?

Nothing, probably! Normally, hardy kiwis and Arctic kiwis are very cold-tolerant climbing plants that produce a lot of fruit, at least, when you have at least one male plant to pollinate up to 8 females. And they’re very adaptable when it comes to growing conditions: you could say, without too much exaggeration, that they’ll grow anywhere! Indeed, they thrive in just about any well-drained soil in both sun and shade.

So why then is it taking yours so long to produce fruit?

Here are a few possible reasons:

  1. It’s too young

If you want to grow kiwis, you have to be very patient. Most won’t even start to flower until they’re about 3 years old and even then, rarely bear fruit in any quantity until they’re 5 to 7 or even 9 years old.

  1. It’s not hardy enough

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The typical supermarket kiwi, Actinidia deliciosa, isn’t hardy enough to produce fruit in many climates. JJ Harrison, Wikimedia Commons

Any kiwi grown in a colder zone than one for which it is recommended will likely never bloom as it flowers from new growth appearing from the previous year’s branches and if they are damaged or killed back by a cold winter, there’ll be no fruit. Therefore you have to plant your kiwi in a hardiness zone to which it is adapted.

The kiwifruit of our supermarkets, with its large hairy fruit, is called A. deliciosa (formerly A. chinensis) and it’s not hardy in cold climates. It grows best in hardiness zones 8 to 9, although it can sometimes succeed in zone 7. In the north, it will only fruit successfully a greenhouse.

The plant usually called hardy kiwi (A. arguta) is indeed quite hardy: usually to zone 4. Despite its hardiness, it’s not the best choice for regions with short summers, as the fruits take about 150 days to mature. Its fruits are small, green and smooth. There’s no need to peel them, just pop them in your mouth, like a grape!

Arctic kiwifruit (A. kolmikta) isn’t really from the Arctic, but it is the hardiest variety (to zone 3) and the best choice for northern gardeners. Its fruit ripens early as well, usually at the end of August or early in September. Its fruits are much like those of the previous species: small, green and smooth. Often, but not always, its foliage is variegated with white or white and pink, making this the most attractive kiwi.

  1. It’s a naturally poor producer

Curiously, the best-selling hardy kiwi by far is also the least likely to bear fruit!

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‘issai’ is commonly sold in garden centers in areas where it simply won’t produce fruit.

The Japanese cultivar ‘Issai’, although sold as a hardy kiwi (A. arguta), is actually a less-hardy hybrid (A. arguta x A. rufa). It’s inevitably offered as the variety of choice for gardeners who don’t have enough space for two kiwi plants, a male and a female, because it’s said to be bisexual. (In fact, ‘Issai’ is 100% female, but is parthenocarpic: it can produce a limited number of fruits without pollination.) It is also said to begin to produce fruits at an exceptionally young age: only 2 or 3 years and is naturally a fairly small, weak grower, taking up less space than other kiwis.

All that sounds good, but it rarely lives up to its hype. While it may produce fruits without a male variety nearby for pollination, expect only a few fruits per plant per year… and expect none at all in colder regions. Although the stems may be hardy to zone 4b, it rarely blooms at all anywhere north of zone 6b and is only likely to be very productive in zone 7 or above. It can be very productive in mild climates, but only in the presence of a male hardy kiwi (A. arguta).

  1. The parent plants aren’t of the same species

When you plant a male kiwi and one or more female kiwis, they must be of the same species. In other words, a male arctic kiwi (A. kolomikta) will, under normal circumstances, only pollinate a female arctic kiwi and a male hardy kiwi (A. arguta) can effectively pollinate only a female hardy kiwi. If your male belongs to one species and the female, to another, you aren’t going to get fruit!

  1. There’s a lack of pollinators in the area

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Bumble bees are the kiwi’s main pollinators. Photo: Buzzy Bee, Kiwi Flickr

Usually, bees pollinate kiwi flowers but not necessarily honeybees (Apis mellifera). Kiwi flowers don’t produce enough nectar for their taste, plus they prefer to visit flowers exposed to the sun, while kiwi flowers are hidden among the plant’s foliage. Bumble bees (Bombus spp.), larger hairy bees, are much more effective pollinators. In fact, kiwifruit farmers are increasingly using commercially-raised bumblebees as pollinators. Where bumble bees are absent, you may have to pollinate your kiwis manually.

  1. A late frost killed the flower buds

This happens when there is a severe frost while the plant is in bud or in flower. Curiously, there is a greater risk of frost damaging kiwi flowers in a mild climate, as plant growth starts up earlier there, even while a risk of frost lingers, than in cold regions, where flowering is naturally delayed until all danger of frost is usually over.


Essentially, hardy kiwis are very easy to grow, but you have to choose the right varieties, plant at least one of each sex of the right species and be very, very patient!20170617A University of Minnesota Extension